新问题 67
注意：本问题是一系列问题中的一部分，这些问题提出了相同的情景。该系列中的每道题都包含一个可能达到既定目标的独特解决方案。某些题组可能有不止一个正确的解决方案，而其他题组可能没有正确的解决方案。
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You have devices that connect to an Azure IoT hub. Each device has a fixed GPS location that includes latitude and longitude.
You discover that a device entry in the identity registry of the IoT hub is missing the GPS location.
You need to configure the GPS location for the device entry. The solution must prevent the changes from being propagated to the physical device.
Solution: You add the desired properties to the device twin. Does the solution meet the goal?
Device Twins are used to synchronize state between an IoT solution’s cloud service and its devices. Each device’s twin exposes a set of desired properties and reported properties. The cloud service populates the desired properties with values it wishes to send to the device. When a device connects it requests and/or subscribes for its desired properties and acts on them.
参考资料
https://azure.microsoft.com/sv-se/blog/deep-dive-into-azure-iot-hub-notifications-and-device-twin/
Topic 1, Contoso
Case Study
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开始案例研究
To display the first question on this case study, click the Next button. Use the buttons in the left pane to explore the content of the case study before you answer the questions. Clicking these buttons displays information such as business requirements, existing environment, and problem statements. If the case study has an All Information tab, note that the information displayed is identical to the information displayed on the subsequent tabs. When you are ready to answer a question, click the Question button to return to the question.
Existing Environment. Current State of Development
Contoso produces a set of Bluetooth sensors that read the temperature and humidity. The sensors connect to IoT gateway devices that relay the data.
All the IoT gateway devices connect to an Azure IoT hub named iothub1.
Existing Environment. Device Twin
You plan to implement device twins by using the following JSON sample.
Existing Environment. Azure Stream Analytics
Each room will have between three to five sensors that will generate readings that are sent to a single IoT gateway device. The IoT gateway device will forward all the readings to iothub1 at intervals of between 10 and 60 seconds.
You plan to use a gateway pattern so that each IoT gateway device will have its own IoT Hub device identity.
You draft the following query, which is missing the GROUP BY clause.
SELECT
AVG(temperature),
System.TimeStamp() AS AsaTime
FROM
Iothub
You plan to use a 30-second period to calculate the average temperature reading of the sensors.
You plan to minimize latency between the condition reported by the sensors and the corresponding alert issued by the Stream Analytics job.
Existing Environment. Device Messages
The IoT gateway devices will send messages that contain the following JSON data whenever the temperature exceeds a specified threshold.
The level property will be used to route the messages to an Azure Service Bus queue endpoint named criticalep.
Existing Environment. Issues
You discover connectivity issues between the IoT gateway devices and iothub1, which cause IoT devices to lose connectivity and messages.
Requirements. Planning Changes
Contoso plans to make the following changes:
* Use Stream Analytics to process and view data.
* Use Azure Time Series Insights to visualize data.
* Implement a system to sync device statuses and required settings.
* Add extra information to messages by using message enrichment.
* Create a notification system to send an alert if a condition exceeds a specified threshold.
* Implement a system to identify what causes the intermittent connection issues and lost messages.
Requirements. Technical Requirements
Contoso must meet the following requirements:
* Use the built-in functions of IoT Hub whenever possible.
* Minimize hardware and software costs whenever possible.
* Minimize administrative effort to provision devices at scale.
* Implement a system to trace message flow to and from iothub1.
* Minimize the amount of custom coding required to implement the planned changes.
* Prevent read operations from being negatively affected when you implement additional services.
